OS X :: Changing Song Info Without ITunes?

I'm sure this is a ridiculously easy thing to do, and that I'm just being exceptionally stupid, but I've not been able to figure it out, and Google is as unhelpful as ever.

As a new PC to Mac convert, occasionally I stumble on something in OS X that baffles the heck out of me, and inevitably discover that it's typical ex-Windows stupidity on my part, and I'm hoping this is just another example of that. I'm looking for a means of changing song information (track number, album, year, genre, &c), without having to use iTunes. I hate iTunes at the best of times, and really don't relish the thought of being forced to use it every time I want to switch two letters of a mislabelled album title or re-number a track (I should also point out, my iTunes library is taken from an external harddrive for the sole purpose of putting that music on my iPod (the only reason why I use iTunes), whereas the songs I want to relabel are on my MBP's harddrive for the purpose of listening to from the computer itself, and are currently not in my iTunes library in any form, nor do I wish to put them there).

In Windows, you could just pull up the file information and change track number, album, year, &c &c &c from within Explorer... but when I try to do the same in OS X by hitting "more info" in Finder, there's no option to change any of the details I'm after. Is there a simple way of doing this that I'm just blindly missing by sheer stupidity, or does song information have to be edited through iTunes or not at all?